Fears of trans women taking over women’s sports simply doesn’t match up with the reality of the effects that transitioning and hormone replacement therapy have on an athlete’s body.

Natalie Washington, a forward for Rushmoor FC, a seventh-tier women's team in Hampshire, recently bundled in her first competitive goal in three years. It was not a thing of beauty.

"It was probably one of the worst goals I've ever scored!" the 33-year-old recalled. "I put the keeper under pressure after a backpass, a defender got in the way, the keeper cleared it into the defender, it bounced off me and went in! I didn't even really feel I could be that happy about it because it was so rubbish."

Her team eventually lost the match 7-3, but for Natalie, who is a transgender woman, just getting back on the pitch after transitioning was an accomplishment.

Until recently, transgender female athletes faced a near-total ban from competitive sport. Fuelled by fears of big, burly men masquerading as women to gain an athletic advantage, governing bodies like the International Olympic Committee and the International Association of Athletics Federation created ridiculous and humiliating sex-testing procedures that remained in place for decades despite little scientific support. It was only in 2004 that the IOC allowed trans athletes to compete in the Olympics (under extensive restrictions that weren't reformed until 2015), and other organisations have followed their lead.

"All the talk of advantage or disadvantage held by trans women misses the most important point," says Harper, who published the first-ever performance study of transgender athletes in 2015. "The most crucial question to ask is this: should trans women and cisgender women compete in the same category? All available research says yes, assuming that trans women have been through an appropriate course of HRT [hormone replacement therapy]". Fears of trans women taking over women's sport simply doesn't match up with the reality of the effects that transitioning and HRT have on an athlete's body. No one knows that better than Natalie.

Natalie, in the yellow jersey, during a recent match // Photo courtesy of Natalie Washington

Natalie took up football seriously at 22, after university, and quickly found a Sunday League team. They we "a mix of overweight men from local pubs wanting to kick people, failed ex pros who never had the attitude, young men looking for something to do and an assortment of others," she said. "I've always been naturally quite fit so that was never much of a problem. I was typically used as a defensive midfielder. I basically ran around a lot, could pass the ball pretty well, and had a decent grasp of positioning and tactical awareness."

When Natalie first planned out her transition four years ago, she says, "to be honest I thought things were probably over competitively. I wasn't sure about whether the rules would allow it [joining a women's team after transition]." She recalls reading a story in the Daily Mail about Aeris Houlihan, a trans woman who was banned from women's football by the FA for two years after she had genital reassignment surgery (GRS).

Natalie was 29 years old at this point and felt she didn't have that many years left of competitive play, anyway. "I stopped playing at the end of the season before I transitioned [in 2013-14] in preparation. I didn't tell most of my teammates why, although of course they found out. So basically I took up running, and hoped that would be enough."

Natalie lost two and a half seasons before she could return to football. In November of 2014, nearly a full year after the Houlihan case made headlines, the FA released a new "Policy on Trans People in Football." In it, the association says it will approve adult athletes to play with their affirmed gender on a case-by-case basis, but the requirements themselves are written without specificity, only stating that trans women must undergo hormone therapy or a gonadectomy and demonstrate that their "blood testosterone [is] within natal female range for an appropriate length of time so as to minimise any potential advantage."

Without a stated standard in the policy, Natalie had to inquire into the specific testosterone levels that the FA was looking for. "They want a blood-tested testosterone level of under 1.5nmol/L for at least a year before you can play," she says. "So the length of time is fairly standard, but the target level is very low [in comparison to other governing bodies like the IOC]."

Medical transitions for trans women begin with HRT, which is a two-part process. The first is a prescription for an antiandrogen, which blocks her natural production of testosterone. The second is a synthetic estrogen like Estradiol, which is also prescribed to menopausal cis women. After Natalie started HRT, there was a gap between where the doctors wanted her hormone levels to be and where the FA required them to be. "This was the problem for me, as my T had [reached] a level that my doctors at the time were happy with, but wasn't low enough to enable me to play," she said. Luckily, there are several different kinds of testosterone blockers, each with different results. "So when my first application was rejected, I had to get my medication changed, which basically annihilated my testosterone level. They [the FA] then said this was acceptable, so I just had to wait another year!"

In addition to meeting the FA's strict rules, the other big challenge for Natalie was dealing with her now drastically changing body as an athlete. At 6'1" and 180 pounds before transition, she was by no means large for a men's side, but as she moved further into her medical transition, she felt her body lose strength.

"I've played five-a-side football against men fairly regularly in the last couple of years too and I'm much less able to compete physically than I was. I was never strong before, but I have even less upper body strength now," Natalie wrote in one of our email exchanges. "I've only ever really done strength work on the lower half, and for the last couple of years that's mainly focused on trying to lose less [muscle], rather than gain any (apart from stupid amounts of squats and lunges in a vain search for any kind of bum)."

Not only has she been less physically able to compete at her former level, she also needs longer rest periods between training. "Recovery has been another surprise – not so much in terms of recovery from injury, but in terms of ability to go again after a period of high-intensity exercise."

Many people underestimate or don't realise how dramatically hormones affect the human body. As Joanna Harper explains, "Once a trans woman starts on antiandrogen drugs as part of HRT, then her testosterone levels quickly fall to female norms. This is followed by a rapid reduction in the percentage of red blood cells in the blood stream, again to female levels. The lower hematocrit levels have a dramatic effect on endurance sports such as running or cycling. The lower T levels also will cause muscle mass atrophy. The loss of strength is not as rapid, nor as complete, as the loss of endurance, but trans women will lose much of their strength advantage over cisgender women."

Hormones don't change everything, of course – something opponents of trans-inclusive policies frequently bring up – and at 6'1", Natalie is taller than the average woman. Then again, so are many cis female basketball players, and no one questions their participation. Not to mention that height isn't a universal advantage: Lionel Messi is 5'7", and in some sports like gymnastics it can even be a detriment. Athletes, like all humans, differ from one another in hundreds of ways, not just in terms of physical traits but also things like access to necessary training resources; some of these confer competitive advantages, but few are policed in the name of a "level playing field" the same way hormones have been, particularly in female athletes.

And while Natalie took up running several months into her transition to improve her fitness, she couldn't outrun all the effects of HRT. She reports being able to finish a 5K in 21:35 with no serious training before starting hormones, but hasn't beaten 22:05 since, despite the fact that she now regularly trains for and competes in half-marathons. And that has significantly affected her game on the pitch.

"It's really struck me that I've lost that explosive first yard of pace," she says. "I used to be able to knock the ball past someone and then chase it down and get there first, most of the time. I can't do that anymore." (Consider, too, that it was against men before, and now it's against women).

"I have heard similar stories to Natalie's over and over again from other trans women athletes," Harper said. "Quickness is very difficult to quantify, but I have little doubt that trans women are at a quickness disadvantage with respect to cisgender women. As an example, Renée Richards [a tennis player in the 1970s] was a better singles player before her transition, but was a better doubles player after her transition. The reduction in T and in hematocrit result in smaller motors powering larger bodies."

"I've lost that explosive first yard of pace," Natalie says // Photo courtesy of Natalie Washington

It's not just her own body that has caused Natalie to change the way she plays. She is also aware of the perceptions of trans women athletes and can be reticent to engage in physical play. "I'm worried about going in too aggressively because of how it might appear to outsiders. It's all driven by a fear of how any sort of physical aggression will be judged in the context of me being a trans woman. Similarly, I tend to avoid hitting shots with power from distance, for the same reason."

"I believe it is fairly common for trans women to be somewhat reticent about trying to physically dominate sports," Harper says. "But girls play tough, and trans women need to be careful. I know of one trans woman who suffered a concussion in a women's rugby match. The story didn't make the news, but it isn't difficult to imagine what would have been said if the trans girl had caused a concussion in one of her opponents."

It's been a long journey to get back on a competitive pitch for Natalie, and her waiting isn't quite over yet. She played in two matches with Rushmoor this year before having her own GRS and will miss the rest of the 2016-17 season. She hopes to recover enough to begin proper training with her club again in August.

Washington's transition and playing career gives us a snapshot into what trans female athletes undergo just to pursue the sports they love. Between the drastically changing body and the bureaucratic nightmare, the obstacles are enough to drive a lot of athletes away; only the most persistent are likely to try to make it work.

"It has been 13 years since the IOC first let trans athletes compete," Harper says. "Trans women have not taken over women's sport, and are still, in fact, grossly under-represented in sport. I met with officials representing international women's rugby in 2016. At that time, six out of 500,000 registered worldwide women's rugby players were trans. Statistically, there should be two or three thousand. Trans women will not be taking over any time soon!"